A hydrocarbon polymer, for example, polyolefin resins such as polypropylene and polyethylene, and a polyolefin rubber such as ethylene-propylene copolymer rubber and polybutadiene rubber are inferior to coatabilities even when the surface of moldings thereof are coated or an adhesive is applied thereon because they don't have a polar group.
To solve the above-mentioned problems of the hydrocarbon polymer, there have been proposed a method of adding polyhydroxypolybutadiene wherein 98% or more of double bonds have been hydrogenated (Japanese Patent Application Publication (JP-B) No. 57-6462), a method of adding a hydrocarbon-based polymer ,such as polyhydroxyhydrocarbon polymer, which contains a hydroxyl group at a molecular end (Japanese Patent Application (JP-A) No. 1-197534), and a method of adding a low-molecular polyisoprene wherein 50% or more of double bonds have been hydrogenated (JP-A No. 2-69545). According to these methods, the coatabilities are improved, while mechanical strength such as flexural elasticity is lowered.
Also there have been proposed methods of modifying the surface of olefin-based resins by adding the modifier such as a polycarbonate diol (JP-A No. 6-172596) and a polyether-ester diol compound prepared by a ring-opening polymerization of a lactone with ethylene glycol (JP-A No. 6-116472). However, according to these methods using the modifier, coatabilities are not sufficiently improved.
As the method of improving coatabilities, there has been proposed a method of adding, to a polypropylene resin, a polyester having a high molecular weight and a high hydroxyl value, which is obtained from an alicyclic carboxylic acid having a molecular structure wherein carboxyl groups are combined with adjacent two hydrocarbon atoms, and a polyhydric alcohol containing hindered glycol (WO99/51660). However, it has been required to make a further improvement in coatabilities.